Function eql [src]

Compares two of any type for equality. Containers that do not support comparison on their own are compared on a field-by-field basis. Pointers are not followed.

Prototype

pub fn eql(a: anytype, b: @TypeOf(a)) bool

Parameters

b: @TypeOf(a)

Example

 test eql {
    const S = struct {
        a: u32,
        b: f64,
        c: [5]u8,
    };

    const U = union(enum) {
        s: S,
        f: ?f32,
    };

    const s_1 = S{
        .a = 134,
        .b = 123.3,
        .c = "12345".*,
    };

    var s_3 = S{
        .a = 134,
        .b = 123.3,
        .c = "12345".*,
    };

    const u_1 = U{ .f = 24 };
    const u_2 = U{ .s = s_1 };
    const u_3 = U{ .f = 24 };

    try testing.expect(eql(s_1, s_3));
    try testing.expect(eql(&s_1, &s_1));
    try testing.expect(!eql(&s_1, &s_3));
    try testing.expect(eql(u_1, u_3));
    try testing.expect(!eql(u_1, u_2));

    const a1 = "abcdef".*;
    const a2 = "abcdef".*;
    const a3 = "ghijkl".*;

    try testing.expect(eql(a1, a2));
    try testing.expect(!eql(a1, a3));

    const EU = struct {
        fn tst(err: bool) !u8 {
            if (err) return error.Error;
            return @as(u8, 5);
        }
    };

    try testing.expect(eql(EU.tst(true), EU.tst(true)));
    try testing.expect(eql(EU.tst(false), EU.tst(false)));
    try testing.expect(!eql(EU.tst(false), EU.tst(true)));

    const V = @Vector(4, u32);
    const v1: V = @splat(1);
    const v2: V = @splat(1);
    const v3: V = @splat(2);

    try testing.expect(eql(v1, v2));
    try testing.expect(!eql(v1, v3));

    const CU = union(enum) {
        a: void,
        b: void,
        c: comptime_int,
    };

    try testing.expect(eql(CU{ .a = {} }, .a));
    try testing.expect(!eql(CU{ .a = {} }, .b));
}

Source

  pub fn eql(a: anytype, b: @TypeOf(a)) bool {
    const T = @TypeOf(a);

    switch (@typeInfo(T)) {
        .@"struct" => |info| {
            if (info.layout == .@"packed") return a == b;

            inline for (info.fields) |field_info| {
                if (!eql(@field(a, field_info.name), @field(b, field_info.name))) return false;
            }
            return true;
        },
        .error_union => {
            if (a) |a_p| {
                if (b) |b_p| return eql(a_p, b_p) else |_| return false;
            } else |a_e| {
                if (b) |_| return false else |b_e| return a_e == b_e;
            }
        },
        .@"union" => |info| {
            if (info.tag_type) |UnionTag| {
                const tag_a: UnionTag = a;
                const tag_b: UnionTag = b;
                if (tag_a != tag_b) return false;

                return switch (a) {
                    inline else => |val, tag| return eql(val, @field(b, @tagName(tag))),
                };
            }

            @compileError("cannot compare untagged union type " ++ @typeName(T));
        },
        .array => {
            if (a.len != b.len) return false;
            for (a, 0..) |e, i|
                if (!eql(e, b[i])) return false;
            return true;
        },
        .vector => |info| {
            var i: usize = 0;
            while (i < info.len) : (i += 1) {
                if (!eql(a[i], b[i])) return false;
            }
            return true;
        },
        .pointer => |info| {
            return switch (info.size) {
                .one, .many, .c => a == b,
                .slice => a.ptr == b.ptr and a.len == b.len,
            };
        },
        .optional => {
            if (a == null and b == null) return true;
            if (a == null or b == null) return false;
            return eql(a.?, b.?);
        },
        else => return a == b,
    }
}  